1. Field of the Invention
The present invention relates to light conducting members having the functions to conduct only beams of light straightly advancing in the direction of a desired optical axis and photoelectric transfer apparatus using such a light conducting member.
1. Description of the Prior Art
As one of the prior arts, such an arrangement in which a light conducting member formed of a bundle of a large number of optical fibers each thereof having a core and clad disposed in front of a photoelectric transfer apparatus is disclosed in U.S. Pat. No. 3,714,447.
In optical apparatus such as photosensor apparatus and optical instruments, there are provided various optical systems.
In optical reading apparatus such as, for example, bar code scanners and facsimile apparatus, there is provided, as is known, such an optical system as shown in FIG. 15, in which an objective lens 3, a condenser lens 4, and a pinhole 5 are each disposed at predetermined spaces apart between a pattern 1 as a material to be read and a photodetector device 2. In this case, after a point light source from the pattern 1 is turned into parallel rays through the objective lens 3, only these parallel rays are converged by the condenser lens 4 to form the image in the pinhole 5 and be read by the photodetector device 2.
In floodlights or the like, it is known that such an optical system as shown in FIG. 16 is provided, in which a condenser lens 7, a pinhole 8 and a collimator lens 9 are each disposed at predetermined spaces apart backwardly of a light source 6. In this case, only parallel rays out of the divergent rays from the light source 6 are converged by the condenser lens 7 to effect image formation in the pinhole 8 and then turned into parallel rays by the collimator lens 9.
There are various types of coordinate input apparatus for inputting coordinates manually in a computer such as those of the electromagnetic type, capacitance type, transparent electrode type, and the photo-detection type. Out of these, what is receiving attention from viewpoints of reliability and operability is that of the photo-detection type, which can be fitted in front of a display apparatus and is adapted such that light paths formed therein are shielded by the finger or the like merely placed on any position on the display surface of the display apparatus, and thereby, the coordinates of that position can be specified without a touch on the detection apparatus itself.
An example of the photo-detection type of the prior art coordinate input apparatus is shown in FIG. 17 to FIG. 19. FIG. 17 is a perspective view showing a state of the coordinate input apparatus mounted in front of a display apparatus, FIG. 18 is a sectional view of the important portion of the coordinate input apparatus at the side toward photodetector devices, and FIG. 19 is a rear view of the coordinate input apparatus with its back board removed so that its internal arrangement may be seen.
In these figures, the coordinate input apparatus is chiefly made up of a frame body 10 shaped into a virtually rectangular form with an opening 12 made in the center portion thereof, numbers of photo emitting devices 14 such as LEDs and numbers of photodetector devices 15 such as phototransistors each arranged in line in the space at the rear of the frame 10, i.e., the space between the frame 10 and the circumferential portion of the display surface 13a of a display apparatus 13 using a CRT (cathode ray tube) or the like, and a processing unit 16 for detecting the position of the shielded optical paths 20 out of all the optical paths 20 formed by combinations of the light emitting devices 14 and photodetector devices 15 situated to oppose each other through the operating area A in front of the display surface 13a and inputting the detected position, the lines of light emitting devices 24 and the lines of photodetector devices 25 forming two sets of opposite sides of a frame formed by the lines of such optical devices 23.
The light emitting devices 14 and the photodetector devices 15 are fixed on a board 17 provided within the frame body 10 so that the light emitting portion 14a and photodetecting portion 15a of each set of them may oppose each other, and further, in front of the photodetecting portion 15a of the photodetector device 15, there is disposed a shield plate 18 with a light inlet opening 18a of a predetermined area made therein so that only the light beam incident from the light emitting device 14 which is the pair of the photodetector device 15 may be received therethrough. Further, in front of such shield plates 18 and the light emitting devices 14, i.e., at the circumference of the operating area A, there is set up an infrared filter 19 along the entire circumference. Therefore, in the operating area A in front of the display surface 13a, there are formed invisible light paths 20 through the infrared filter 19.
The inputting principle of the coordinate input apparatus of the above described construction will now be explained. Supposing that the finger 21 is placed in touch with the display surface 13a at the position desired to be input as shown in FIG. 17, the light paths 20 which are to go over that position are shielded by the finger and the coordinates of the position can thus be specified. More particularly, it is adapted such that the shielded paths 20 in both x and y directions are detected by the photodetector devices 15 by successively lighting, or scanning, the light emitting devices 14 of the lines of light emitting devices 24, and these paths 20 are specified by the processing unit 16 and the coordinate values thereof are input to a host computer not shown.
As examples of the prior art optical reading apparatus for optically reading recorded images such as a bar code provided on a material to be read, there are disclosed bar code reading arrangements in the publication of Japanese Laid-open Utility Model No. 54-170,735, the publication of U.S. Pat. No. 3,809,893 etc.
Such bar code scanner will be described with reference to FIG. 20, in which 26 denotes a body in a virtually cylindrical form as a whole except the front portion in a cone form, 27 denotes a retainer disposed within the body 26, and 28 denotes a light beam path 28 provided bored in the center of the retainer 27 extending in the axial direction. Reference numeral 29 denotes a light emitting device such as a light emitting diode attached to the front end of the retainer 27, 30 denotes a lens disposed at one end of the light beam path 28, 31 denotes a photodetector device such as a phototransistor disposed at the other end of the light beam path 28, and 32 denotes a pinhole disposed in front of the photodetector device 31, and the photodetector device 31 is connected to a print board (not shown) with various electronic parts for processing circuits mounted thereon.
In reading a bar code printed on a material to be read 33 with the bar code scanner briefly described above as to its construction, the light beam from the light emitting device 29 is thrown on the material to be read 33. Then, the reflected light from the material to be read 33 is converged through the lens 30 to form the image in the pinhole 32, and then allowed to enter the photodetector device 31. By processing the output signal from the photodetector device 31, the bar code can be read out.